SOLUTION: cos 9pi/12 cos 3pi/12 + sin 9pi/12 sin 3pi/12

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Question 1083978: cos 9pi/12 cos 3pi/12 + sin 9pi/12 sin 3pi/12
Answer by Alan3354(69443) About Me  (Show Source):
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cos 9pi/12 cos 3pi/12 + sin 9pi/12 sin 3pi/12
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cos(A-B) = cos(A)cos(B) + sin(A)sin(B)